The Aegolius

He saw a lot of cases of missing children.
But he never thought it would happen with him.One hour Cassie was by his side and the other she was gone.
He thought she was gone forever,taken away from him.
But then she showed up, claiming a Owl guardian had found her and helped her find her way home again.
He had heard tales of it,of course.The whole town knew about it.
The Aegolius,an owl looking creature that would help lost children.
Of course he couldn't just let it go after that.He would find out who helped those poor kids.
Because,obviously, there's no such thing as guardian spirits or whatever people thought it was.
He would find out who this person was.But the thing is...

What if it truly isn't a person?